Survey posted 2006-06-04 05:28 by Jon.

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I suppose this is relevant...

I stumbled upon a picture of the guts of a TI-81 and it looks like it has a spot for a linking port at the bottom. I wonder if it's possible to put one on and send data to it?

see url

it couldnt hurt to try...although i doubt it would be possible.

i'd just get a used 81 on ebay and experiment with it

Experiment on it? As a proud owner of an overclocked 81, I'm offended! :). Anyway, I still think it's funny that an overclocked 81 is faster than a 84+SE!

Overclocked?

Never mind.

I'm going out on a limb here and assume TI-OS for the 81 does not offer linking functionalty (as in, the "Link" menu doesn't exist). Therefore, to use the newly installed link, you'd need an assembly program, so you can directly poll the appropriate port.
Well, there's an interesting chicken-and-egg problem here... Because it's an old model, it has no native support for running user-written assembly programs. So, you would need to use the 85 trick of messing with a backup file if you're going to get assembly to work. But ehm, to send (or, for that matter, receive) a backup file, you're gonna need a funtioning link port...

Not that I wouldn't ROTFL if, anno 2006, somebody got assembly on the 81 to work (can a dutchie translate: "mosterd na de maaltijd" ;) ), especially if it's just because he wanted to get the link port to work (which the 81 wasn't even supposed to have in the first place)!

Hmm, wait a minute, there might be a way to get your newly installed link port to do something useful!

I mean, if that spot on the board was actually intended for a link port, then I guess the developers also put in the necessary code in the OS. At some point, probably just before it went into production, the link port was canceled. Now, if I had to remove some functionality from an embedded device, I'd just remove all the references to it from the UI, but leave the code there (why bother removing it, right?).

Now, if the code is there, you could attempt to get to the "unreachable" linking code. There are a number of commands (at least on the TI-83, not sure about the TI-82, let alone the TI-81 :p ), that don't need input from the calc. Those commands together are known as "silent linking"; requesting a list of files that are currently stored on the calc, pushing a file onto the calc or fetching a file from the calc. Contrary to what I said in my previous post, you can also get (and, IIRC, send!) a backup with silent linking. There even is a way to send key presses to a calc over the link (which can be used as kind of a "remote control" feature), which, admittently, isn't gonna do you any good, but still looks massively cool.

It seems unlikely that the 81 would have any linking code at all, but then again I have no way of checking, since I don't have an 81.

Also, TI-80 could have a port, too. Maybe that has silent code since it's newer.

If you look at the picture of the "second series" of the TI81, you can clearly see that the location of a link-port-sized component is drawn, together with three terminals (a link port happens to need three terminals: ground, wire 1 and wire 2). Personally, I'm convinced that TI at one point intended to include a link port on that circuit board.
Whether or not there's any linking code in the TI-81's ROM is a different matter, but I think there's a fair chance... I mean, there's no point to add hardware if your OS can't support it; why draw a link port on your circuit board if you have no intention to write linking code into the OS?
On the other hand, there was quite clearly a reason the link port was scrubbed at some point. What that reason was remains open to speculation ofcourse. If the port was removed from the final design because the code people couldn't get the link to work properly, then any code that might still be in the OS is probably not gonna be useful. On the other hand though, if the marketing people were afraid two versions of the TI-81 (I couldn't find any indication of a link port being considered for the "first series") would confuse users too much, there's a pretty good chance the OS actually does support linking. The easiest way to remove the planned link port would've been to not install the hardware and comment out the lines that would call the linking menu when a certain key is pressed. The first problem can be solved by installing the link port yourself, the second by not going through the menus (but instead, use silent linking for example).

Now, your other point is ofcourse very valid; if this was the first calc to support linking (and that feature didn't even make it into the final design) odds are whatever link functionality was originally planned is probably not all that sophisticated (read: no remote control). But that doesn't mean there is nothing whatsoever. If you can emulate (aka fake) a GraphLink file transfer it might still be succesful...

Wow, that *does* look like a link port goes there...I don't know if TI would've even added silent linking or remote control on their *first* graphing calc, though. I mean, I don't think silent linking was used on even the calcs that *did* support linking for a while, so unfortunately I doubt the '81 would have it. The remote control also seems like a sort of side feature, not something they would do on the 81. Worst case, you could unsolder the ROM and try to read and disassemble the contents to find how to get to the linking code, if it's in there, just substitute your own flash or EEPROM chip with a modified version of the ROM contents. Maybe I should get an 81 myself and mess around with this...

Is silent linking when you don't have to put the TI calculator on linking mode?

Right. So even if the 81 did have some linking code, unfortunately you couldn't send files to it since there's no way to put it into recieve mode.

Gotta love DATAMATH!

Does fiddling the with the link port count? ;)

Does destruct the screen count?
/I love the 3-year warranty)

I thought a warranty is terminated as soon as you mess around with the hardware.

...but you don't have to tell them that you messed with the hardware, do you?

Seriously, though, the warranty is valid sometimes, depending on what you do. Obviously, changing the batteries doesn't invalidate it, so they can't just say "if you do anything with the calc's hardware, then the warranty is invalid." They have to specify situations, and I'm sure they left out some things.

I'm no electronic wiz and i'd never fiddle with my calc NEVER!

So you would?

I think he meant to put a comma before the 2nd NEVER... but I see what you mean, he used "double negatives".

Well, when talking about double negatives there's quite a difference between natural languages and formal languages. In formal languages a double negative is a positive, period. In natural languages, it's very common for a double negative to be a "very-negative" or "negative-and-no -doubt-about-it" (a concept which has no counterpart in formal languages anyway).